In a world where humans coexist with creatures called Yoma sentient monsters that feed on human guts, a nameless and highly secretive organization has created an order of half-human, half-yoma warriors to protect humans from the yoma, for a large fee. The people of this world have dubbed these warriors as "Claymores" based on their gargantuan, unsheathed swords. The story surrounds one Claymore warrior, Clare, and her quest for vengeance.